Pressure gauge



March 1, 1932. A. F. SPlTzGLAss PRESSURE GAUGE Filed April 13. 1925 ,f d n aumwwill QISFME n =Ewww@ Patented Mar. 1 1932 UNITED STATES PATENT OFFICE ALBERT F. SPITZGLASS, OF CHICAGO, ILLINOIS, ASSIGNOR 'IO REPUBLIC FLOW METERS CO., OF CHICA-G0, ILLINOIS, A CORPORATION OF ILLINOIS PRESSURE GAUGE 1 Application mea April 13, 1925. seri-a1, No. 22,582.

This invention relates to mechanism Jfor indicating or recording pressure differences and is designed especially for measuring Variations in the hea-d of liquids.

The invention has for its object the provision of a pressure measuring device which shall be economical to manufacture and install, and which shall be of improved construction and operation.

The invention is exemplified in the combination and arrangement of parts shown in the accompanying drawings and described in the following specification, and it is more particularly pointed out in the appended 15 claim.

In the drawings,

Fig. 1 is a somewhat diagrammatic view showing one manner of installing the present invention.

Fig. 2 is a vertical sectional view of the U-tube apparatus and resistance element forming a part of the invention.

`ig. 3 illustrates a diierent manner of installing the apparatus from that shown in Fig. 1. Y

The instrument comprises a U-tube mechanism including a base block 10, which may be made of steel and into which pipes 11 and 12 are threaded. The smaller tube 12 may be made of seamless steel and the larger tube 11 may be ordinary galvanized iron pipe. bushing 13 surrounds the tube 12 and bears upon packing rings 14, which insure a tight connection between the block 1() and the tube 12. The block is provided with a smaller tapped opening within the opening for the pipe 11, and a. tube 15 is threaded into this smaller opening. Packing rings 16 surround the tube 15 and are held in place by a collar 17, which is welded within the lower end of the pipe 11 and is thus pressed down upon the packing ring`16. The tube 15 is preterably made of suitable insulating material, and is provided with a winding of resistance wire 18 upon its outer surface. A series of metal pins 19 are driven through the outer wall of the tube 15 and ext-end into the tube| a suflicient distance to permit the inner ends 50 of the pins to penetrate slightly into the inner face of the opposite wall of the tube.

The lower end of the winding 18 is secured to a suitable fastening 20 at the lower end of the tube 15, the intermediate points of the windings are connected to the pins 19, while the upper end of the-winding is connected by a screw 21 with a binding post 22. rIhe binding post 22 is provided with a. perforation `23 to connect the upper end of the tube with the atmosphere. A washer 24 of dielectric material surrounds the binding post 22 and holds the upper end of the tube 15 and the binding post from engagement with the metal casing comprising the pipe 11. A metallic outlet boX 25 is supported on the upper end of the pipe 11 and is provided with a binding post or screw 26 to which a lead wire 27 is connected. A lead wire 28 is connected with the binding post 22 and both wires extend from the outlet box to ar suitable source ot electrical current and to indicating instruments. These instruments, as shown in Fig. 1, may include an indicator 29 and a recorder 30. The instruments may be of the ammeter type or any suitable character for indicating current liowing in the circuit. In practice it hasv been found desirable to use alternating current of about ortyvolts in connection with an instrument of the nature shown in the patents of Ernest H. Freeman, Nos.

A 1,568,970 dated Jan. 12, 1926 and 1,768,553

July 1, 1930. Other forms of electrical indicating and recording instruments may of course be used. The block 10 is bored as shown at 31 to form a connection between the tubes 12 and 15, and a vided to close the opening through which and recording the l plug 32 in prothe horizontal drilling is formed and this also provides means for giving access to the interior of the instrument, if desired. Mercury is enclosed` in the U-tube arrangement provided by the tubes 12 and 15 and the block 10, and the upper end of the tube 12 is subjected to the pressure to be measured, while the upper end of the tube 15 co1nmunicates with the atmosphere. It will be apparent that the mercury will rise in the tube v15' to different heights, depending upon the pressure in the tube 12. As the mercury rises in the tube 15, increasing amounts of the A`resistance 18 Will be short-circuited, thus upon the action of the instrument.

changing the total resistance in the electrical circuit which will produce a corresponding reading in the instruments. The instruments are preferably calibrated to read directly the liquid head which produces the pressure in the tube 12. It should be noted that the pins 19 extend entirely across the bore of the tube 15. This has an important bearing It has been found that where the contact members merely project into the tube that mercury will cling to the stub Vends of the contacts as the level recedes, thus the circuit will not e broken When the mercury clears the contacts, conversely when the mercury in the tube rises it contacts With the mercury adhering to the contacts before -it reaches the contacts. This delayed breaking and premature closing of the circuit, through the contacts, causes thc instruments to give inaccurateindications. Where the contacts eXtend entirely across the tube a good connection is made and the mercury does not adhere to the Walls as the leV-el rccedes and the instruments indicate accurately. The pins may be so spaced and the resistance so distributed that the reading of theinstrument will be directly proportional to the pressure on the mercury in the tube 12, or the resistance may be so distributed as to give a reading proportional to the square root of the height of the mercury column, or to any other function desired. It Will be apparent that the range of the instrument need be only suiicient to correspond to the maximum variation in the head of liquid to be measured. Connection may be made at the point adjacent the minimum liquid level and the instrument made to indicate the level at the point Where the instrument is connected plus the head above that point. yWhere the U- tube apparatus is submerged in the liquid, as indicated in Fig. 1, a very simple method of installing is provided and one which insures against freezing of the instrument since it is always submerged in the liquid. It is, of course, not necessary to submerge the U-tube in the liquid', but the tube may be located at any desired position and connection made with the body of liquid by means of the pipe connected to the upper end of the tube 12, as indicated at 33 in Fig. 3. The electrical instruments may, of course, be placed at any convenient position as connection is made by electrical conductors between the indicating instruments and the U-tube. In some cases it may be desirable to omit either the indicating or the recording instruments and this may be done Wherever a single instrument Will serve the desired purpose. claim:

A pressure measuring instrument comprising a base member, a tubular member mounted on said base member, a second tubular member of dielectric material also mounted on said base member, the openings in said tubular members being connected by means of an opening in said base member, a resistance element Wound around said second tubular member, contact members extending from the outside of last last-mentioned tubular member to the interior thereof, said contact members being spaced lon gitudinally of said last-mentioned tubular member from said resistance, leads operatively connecting said contact members With spaced points along said resistance, a third tubular member surrounding the tubular member which has the resistance thereon, a binding post located at the end of said tubular member which carries the resistanc^, a connection between said binding post and said resistance, a conducting fluid in the iirst and second-mentioned tubular members, and an electrical connection leading to said conducting iuid, said electrical connection and said binding post adapted to be operatively connected to an electrical instrument which indicates the amount of pressure exerted on the conducting Huid in said tubular member.

In testimony whereof I have signed my name to this specification on this th day of April, A. D. 1925.

ALBERT F. SPITZGLASS. 

